| dc.description.abstract | Due to theoutstanding mechanical properties and excellent biocompatibilityof Zirconia(ZrO2), the use of zirconia-basedceramics in dental and orthopaedicapplications has grown rapidly over the last decades.One of the major concerns is the long-term reliability of ZrO2as the tetragonal(t)to monoclinic(m)phase transformation, whichaccounts for the exceptional fracture toughness of ZrO2, can spontaneously occur at low temperatures in the presence of water.
A solution to this problem is to dope the Zirconia with ceria (CeO2), instead of yttria(Y2O3), which increasesitsresistance to low temperature degradation (LTD)substantially, although decreasing itshardness significantly. Based on this, the main goal of this work has been tostudy the adherence ona 3 mol. % -ZrO2(3Y-ZrO2also known as 3Y-TZP)supplied by Saint-Gobain –Research Provence Cavaillon (Cavaillon, France) substrate oftwo differentceria-stabilized zirconia coatings, to increase LTD resistance, with different grades ofalumina phase that increasesthe hardnessof the coatings, by means ofdip coatingtechnique. The effect of the speed of the process and the ceramic chargeof the slurry has been studied.
The present work has shown that the Vickers hardness of the ‘Shock’ samples is consistent withthe reported data while the ‘Intense’ samples have not sintered successfully, therefore, the data gathered is unreliable.The roughness profilometer measurementsshowa positive correlation between the roughness parameters (‘Ra’ and ‘Rq’) of the samplesand the dip-coating speed of the process, which is independent of the ceramic chargeof the slurry.The thickness of the coatings increased as the ceramic chargeof the slurries increased. With the aim of achievinglow ‘Ra’, ‘Rq’ and thicknessinthe coatings, specimens at which the process was carried at 5 mm/s with ceramic chargesof 55%, 60% and 65% yielded the best results. Additionally, the thickness of the coatings seemedto converge at 350 μm. It is suggested that at higher speeds the excess slurry is spurted, while at heavier ceramic load slurries will make the excess coating spurt by its own weight. Finally, from theimages showing the scratch tests, it can be extracted that the ‘5S60’, ‘10S65’ and ‘15S60’ samples showed the best behaviour.In conclusion, ‘5S60’samples were the best candidates in order to develop a protocol with commercial usefor these coatings. |
